Method for separating hydrocarbons and making mercaptans



Oct. 16, 1945.

D. E. BADERTsC-HER ETAL l .2,386,772

METHD FOR SEPARATING HYDROCARBONS AND MAKING MERCAPTANS Filed June 29, 1945 z'sneets-sheet 1 cal. @www Re Y od E Tuff N .NHL R Wnw fo m m NQS wm, 595D @Si Oct.; 16, 1945. D. EQ BADERTSCHER ETAL i 2,386,772

METHOD FOR SEPARATING HYDROCARBONS AND MAKING MERCAPTANS Filed June 29, 1943 2 Sheets-Sheet Lu" g k 'Q3 Q .5

ATTORNEY Patented Uct. 16, 1945 UNITED STATES PATENT OFFICE METHOD FOR SEPARATIN G HYDROCAR- BONS AND MAK'ING MERCAPTAN S Darwin E. Badertscher, Woodbury, N. J., Harry L. Coonradt, Camp Lee, Va., and Duncan J. Crowley, Penns Grove, N. J., assignors to Socony-Vacuum Oil Company, Incorporated, a corporation of New York Application June 29, 1943, Serial No. 492,670

. tion may be employed to treat a mixture of hy- 19 Claims.

This application is a continuation-in-part of our application Serial No. 461,116, led October 7, 1942, and has to -do with av selective catalytic method for eiecting the separation of certain olens from hydrocarbon mixtures. More specifically, the present invention has to do with a vapor phase, catalytic treatment of a hydrocarbon mixture with HzS whereby only those hydrocarbons of a sub-class of olens, hereinafter defined as the tertiary base olens, are converted to their corresponding mercaptans.

It is well known to those familiar with the art that olefins will react with HzS in the presence of various catalysts to. form mercaptans. For example, it has been suggested that olelns of at least eight carbon atoms will react in the liquid phase in the presence of certain catalysts, at time intervals of from 6 to 72 hours, to form sulfurcontaining compounds including sulfides and mercaptans. 'I'he present invention distinguishes over the foregoing in that our catalytic treatment is carried out in the vapor phase with a very brief contact time which may vary from a fraction of a second to about several minutes. It has also been suggested (U. S. Patent 1,836,170) that liquid olens will react with HzS in the presence of certain catalysts, such as sulfuric acid, at temperatures within the range of 32 F. to about 100 F. C. to about 38 C.) to form sulfur-containing compounds including mercaptans. The present invention distinguishes over this teaching in that our catalytic treatment with sulfuric acid is carried out in the vapor phase and is extremely effectivelat temperatures in excess of the foregoing temperature range.

Another fundamental distinction between previously proposed processes and the novel process of the present invention is predicated upon our discovery that the catalytic process contemplated herein is selective for the conversion of certain olens to their corresponding mercaptans. For example, the present invention is based upon the discovery that the C-4 and C-5 tertiary base olens, isobutylene, trimethyl ethylene and unsymmetrical methyl ethyl ethylene (of which the latter two are tertiary base amylenes), contained in a mixture of hydrocarbons are converted to their corresponding tertiary mercaptans when the hydrocarbon mixture in the vapor phase and in admixture with H2S is passed over a suitable catalyst with the temperature of the catalyst or reaction zone maintained within certain preferred limits,'depending upon the nature of the catalyst, the pressure in the reaction zone, etc.

Accordingly, the process of the present inventhose oleiins characterized by the presence of the tertiary olefin linkage where R is a low molecular weight alkyl group,

such as methyl. Typical members of this class, and preferred herein are isobutylene,

. and trimethyl ethylene The present invention also provides a highly effective and economical methodl for obtaining the individual tertiary mercaptan from its corresponding tertiary base olefin, i. e., tertiary butyl mercaptan from isobutylene, and tertiary amyl mercaptan from trimethyl ethylene and unsymmetrical methyl ethyl ethylene, respectively. These tertiary mercaptans may be obtained as an incident to the separation of the corresponding tertiary base olefins from a hydrocarbon mixture as aforesaid, or they may be obtained by the vapor phase reaction of the pure tertiary base olen with hydrogen sulde under similar conditions in the same catalytic environment.

The catalysts which we have found to be eective for the purposes of this invention are the following: acids and thioacids of phosphorus and their anhydrides and thioanhydrides, elementary (red) phosphorus, sulfuric acid and organic sulfonic acids, non-plastic clay-type catalysts typified by fullers earth; alumina-silica ty-pe synthetic catalysts and halogenated acids, such as trichloracetic, etc. For the purposes of the present invention, preference isgiven herein to sulfuric acid and organic sulfonic acids; other cata- Illustrative of the organic sulfonic acids which serve the purposes of this invention are benzene sulfonic acid, p-toluene sulfonic acid, tertiary butyl sulfonic acid, etc. Particularly preferred of such acids is benzene sulfonic acid.

We have discovered that the reaction of hydrogen sulfide with a tertiary base olefin to form a tertiary mercaptan by the process contemplated herein is quite sensitive to temperature as a means for controlling the yield of mercaptan, and it is a further important object of this invention to provide a process of the class described wherein the temperature is controlled to afford a maximum yield of the mercaptan.

Further details in a preferred procedure for carrying out the process contemplated by this invention may be obtained from the following description taken with accompanying drawings, which are chosen for illustrative purposes only and in which: Figure 1 is a diagrammatic view illustrating one form of apparatus which may be employed in practicing the process of this invention; Figure 2 is a sectional elevation showing in enlarged detail a typical form of reactor which may be employed in the system shown in Figure 1; and Figure 3 is a graph with curves A and B showing the e'ect of temperature variations upon the yield of tertiary butyl mercaptan in the process contemplated herein.

In Figure 1, reference numeral II indicates a reactor which is shown in Figure 2 as embodying a shell I2 which may be of circular or other suitable cross-sectional shape, such shell being provided near its top with a partition plate I3 having a plurality of openings I4, which receive the upper ends of tubes I5 secured therein in any suitable manner, such as welding (not shown). The lower ends of the tubes I5 are supported in openings I6 through a bottom partition plate I1 secured near the bottom of the shell I2 in any suitable manner so as to form a chamber i8 in the shellV between plates I1 and I3. For the purpose of controlling the temperature within the tubes I5, a suitable heat exchange medium is circulated through the chamber I8 from an inlet 20 to an outlet 2|.

The top of the chamber or shell I2 is provided with a cover 22, which with the top partition plate I3 forms achamber 23 in the top of the shell adapted to receive reaction vapors through an inlet 24, which vapors enter the various tubes from the chamber 23, as indicated by the arrows. The bottom of the shell I2 is provided with a bottom cover 25, through which the products of reaction pass from the tubes I5 into the product outlet 26.

The bottoms of the various tubes I5 are provided with a suitable mesh material to support a body of catalyst indicated by the stippling in Figure 2 within these tubes. 'I'his mesh material may be supported in any suitable manner and, as shown in Figure 2, comprises a screen supported beneath the bottom plate I1 by a similarly perforated plate I1'.

As aforesaid, the reaction contemplated herein is quite sensitive to temperature control; and although the length and size of the reaction tubes I5 and the relation between the total volume of the chamber I8 and the volume within such chamber which is occupied by the reaction tubes may be varied over relatively wide limits, it is to be understood that the relationship between these various factors, the temperature of the heat exchange medium, and the rate at which the heat exchange medium is circulated through the chamber I8 should be so adjusted as to maintain the temperature in the reaction zones of the various catalyst tubes I5 Within the range for most efficient operation, as will be hereinafter discussed.

Referring back to Figure 1: reference numeral indicates a conduit adapted to carry hydrocarbons through a meter Minto the reactor inlet conduit 24.v This conduit is shown as passing through a pre-heater or vaporizer 32 through which a hot heat exchange medium is circulated by means of connections 33 and 33'. Hydrogen suliide is introduced into the system through the valved connection 35 and a meter M', such hydrogensulfide being optionally introduced into the inlet 24 on either side of the vaporizer 32 by means of valved connection 36 or 36'.

With regard to the vaporizer or pre-heater 32, it is to be understood that other suitable means may be provided for insuring that the reactants are in the vapor phase when they pass into the catalystA tubes in the reactor. For example, it may be found, particularly after the reaction has been started, that there is sufflcient heat in the reactor itself to effect this vaporization, or heater coils may be provided in the chamber 23, as will readily appear to those skilled in the art.

Suitable means for controlling the temperature of the heat exchange medium entering the reactor through inlet 20 are indicated by reference numeral 40. The temperature-control means 40 may be any suitable heat exchange device and can be either manually or automatically operated in any manner well known to those skilled in the art. Also, if desired, the heat exchange medium may be recirculated from the outlet 2I through the temperature control 40 to the inlet 20 as will be obvious to those skilled in the art. Any suitable heat exchange medium, such as Water, may be employed to control the temperature in the chamber I8 of reactor II.

Reference numeral 4I indicates a cooler or condenser through which the product-outlet conduit 26 passes into conduit section 26', which opens into a sealed receiving chamber 21. The cooler or condenser 4I is provided with an inlet 42 equipped with temperature-controlling means 43 and with a heat exchange medium-outlet connection 44. The temperature of the cooler 4I may be controlled through the control 43 so as to condense substantially all of the mercaptan which can then be withdrawn together with the polymerization products of reaction from the sealed chamber 21 through a valved liquid-outlet connection 45, or such temperature in the cooler 4I may be controlled so that only the high boiling products are condensed, substantially all of the mercaptan together with the hydrogen sulfide and hydrocarbon gases being conducted in such case from the sealed chamber 21 through a vapor-outlet conduit 41 to the bottom of a scrubbing tower 48.

'The top of the scrubbingtower 48 is provided with a gas vent 50 and an inlet conduit l for a scrubbing solution such as aqueous caustic soda. 'I'he bottom of the scrubber 4B has an outlet 52 which connects with the bottom of a still or stripper A54. Outlet connection 52 is equipped with a drainage valve 53. 'Ihe still or stripper 54 is shown as being equipped with a high-pressure steam coil or other suitable source. of heat 55 and has anoutlet 56 which connects through a condenser 5l with a separator 58. The separator 58 is provided with a valved mercaptan outlet 59, a gauge glass 13 to facilitate removal of the mercaptan, and a valved water outlet 55. The water outlet 85 connects through a valve 5l with a water return pipe 62, which-in turn is shown as connecting with the caustic reservoir 6l. The still 54 is shown as being equipped with a caustic outlet conduit 54 which includes a liquid caustic well 54', the purpose of which is to prevent; mercaptan vapor from leaving still 54 by the conduit 64. Caustic passes through conduit 64 to a caustic cooler 55 and exits therefrom through outlet 6B to the caustic reservoir 6l. The caustic reservoir is fitted with a drainage means 68. The caustic reservoir is also equipped with a conduit 69 which connects with the intake side of a pump 63. The discharge side of pump 63 is shown as connecting with inlet conduit 5| of scrubber 48. Means indicated at 70 are provided for adding fresh caustic when desired; and means indicated at 'H are provided for adding fresh Water to the system. A water drain is shown at 72, and the last-described connections are shown as being provided with suitable valves for controlling the addition or discharge of the various media.

In practicing the process contemplated herein with an apparatus of the type shown in Figures 1 and 2, the tertiary base olefin, either alone or in admixture with other hydrocarbons, and the hydrogen sulfide are metered into the system through meters M and M'. The proportions of these two reactants may be varied over relatively Wide limits, but for optimum results it is preferred that these proportions be such that the hydrogen sulfide be slightly in excess of the molar equivalent required to react with the tertiary base olefin present.

The admixture of hydrocarbon and HzS is introduced into the reactor Il in the vapor phase, as by passing the hydrocarbon through the vaporizer 32 prior to admixture with HzS. Upon entering the reactor il, the hydrocarbon-Hrs vapor mixture passes through the catalyst tubes l5 Where it contacts the `catalyst for a short period of time. It is a feature of the process contemplated herein that the period of catalyst contact is very short. With a catalyst of the type described hereinabove, contact times of from about a fraction of a second to about several minutes serve the purposes of this invention, but in general, a contact time of a few seconds is preferred. The temperature of the heat transfer medium in chamber I8 is controlled by the temperature control 40 so that the temperature of the catalyst zone within the tubes I5 is maintained within the range that will give the desired conversion. As aforesaid, the process contemplated herein is quite sensitive to temperature. We have found, for example, that the process is operative between the limits of atmospheric temperature (at about,25 C.) land about 100 C., but for optimum conversion a more closely defined range of temperature is necessary. This will be tail hereinafter.

When in contact with the catalyst in the' catalyst tubes l5 under the conditions described herein, the tertiary base olen reacts with the hydrogen sulfide in the reaction mixture to form the`corresponding tertiary mercaptan. For example, when the hydrocarbon used is isobutylene, tertiary butyl mercaptan is formed and also a small amount of higher boiling materials which are mainly polymers of'isobutylene. Thus, the eluent gases leaving the reactor H through discharge conduit 26 contain tertiary butyl mercaptan, high boiling materials, traces of unreacted HzS and traces of unreacted isobutylene. Similarly, when the hydrocarbon used is tertiary base amylene, tertiary amyl mercaptan is formed and the eiiiuent gases will contain unreacted HzS, unreacted tertiary base amylene and polymers of said amylene in addition to this mercaptan. When the hydrocarbon used is a hydrocarbon mixture containing a tertiary base olefin (or tertiary base oleflns), such as for example isobutylene, secondary oleflns, normal oleflns, and saturated hydrocarbons, only the tertiary base olen (or tertiary base oleflns) is converted to the corresponding mercaptan. Other hydrocarbons in th mixture are unelected by contact with the catalyst and H28. With such a hydrocarbon mixture, the effluent gases contain tertiary butyl mercaptan, higher boiling materials which are predominantly polymers of visobutylene, traces of unreacted HzS and unreacted isobutylene, and unreacted hydrocarbons, such as normal olefins, secondary olefins and saturated hydrocarbons.

In either case, the ellluent gases flow through the discharge conduit26 to the condenser 4I. As aforesaid, the temperature of the condenser may be maintained such that only the high boiling products are condensed, in which case, the condensate ilows into the sealed chamber 21 and from which it can then be withdrawn through the outlet connection 45. The unreacted hydrocarbons, unreacted HzS and the tertiary mercaptan, such as tertiary butyl mercaptan, are not condensed when such a temperature is main'- tained in the condenser 4|, and ow through the vapor-outlet conduit 4l to the bottom of the scrubbing tower 48. If desired, the temperature of the condenser 4I may be adjusted so that the discussed in further de- -greater portion of the tertiary butyl mercaptan is condensed along with the high boiling materials. This condensate withdrawn through connection 45 may then be distilled in a suitable distillation tower (not shown) to separate the tertiary mercaptan from the polymerization products.

The uncondensed portion of the reaction mixture rises in the scrubber 48 and contacts a downstream of scrubbing solution, such as aqueous caustic soda whereupon tertiary mercaptan (butyl or amyl or both, depending on the tertiary base olefin or oleflns in the charge.) and hydrogen sulfide are converted respectively to the corresponding soluble alkali mercaptide and alkali sulfide or hydrosulde. The unreacted hydrocarbons are unaffected by the caustic soda and are removed through the gas vent 5D from which they may be conducted to another operation or treatment such as alkylation, polymerization, or the like. The alkali mercaptide and alkali sulfide or hydrosulfde in caustic solution pass out of the scrubber 4B through the outlet connection 52 to the still 54. High-pressure steam or other heating medium passes through the coil 55 in the still 54,

thereby heating the caustic solution'to an clevated temperature. On heating the caustic solution., the alkali mercaptide is converted to the corresponding tertiary butyl or tertiary amyl mercaptan which, along with lsome water, distills from the solution. The tertiary mercaptanwater vapors rise to the outlet line 56, flow therethrough to the condenser 5l where they are condensed and from which the condensate flows to the separator 58. 'I'he condensate separates herein (58) into an upper layer of mercaptan, and lower layer of water. The mercaptan layer' is withdrawn through the valved outlet 59to storage or other process, or processes, a gauge glass 13 being provided to facilitate the mercaptan withdrawal.

It will be apparent from the foregoing that when the original hydrocarbon mixture contains a mixture of the preferred tertiary base oleilns, isobutylene and trimethyl ethylene. for example, the mercaptan layer withdrawn through the valved outlet 59 will be a mixture of tertiary butyl and tertiary amyl mercaptans. These mercaptans can then be separated' from each other by suitable separation means, such as by distillation (means not shown). I

The lower water layer is allowed to drain from the bottom of the separator 58, through the wateroutlet 60. It is recombined, in passing through the valve 6| and the water-return pipe 62, with the caustic solution which has been discharged from the still 54. 'I'his caustic solution has passed through conduit 64, well 64', cooler 65,

conduit 66 to caustic reservoir 61. This cold caustic solution, which contains some alkali sulde, combined with water from the separator 58 is pumped by means of the pump 63 to the caustic scrubber 48 through the inlet condiut 5l. If, however, said caustic solution from the still 54 tends to accumulate an appreciable amount of alkali sulfide, it can be removed from the system by means of the drain 68, and can be replaced with a desired amount of fresh caustic through the means 10. This is necessary when an appreciable amount of unreacted HzS is present in the effluent gases from the reactor Il and which reacts with caustic soda in the scrubber 48to form alkali sulfide. If it is necessary to introduce additional water into the system to add to the caustic solution cooled in the cooler 65, fresh water can be introduced through the means 1 I.

The selective action of H2S upon tertiary base olens, such as isobutylene and isoamylenes, is influenced by a number of factors such as temperature, pressure, contact time and rate of flow of reactants, proportions of reactants, the catalyst'used, etc. As We have previously indicated, temperature is the most important and most critical of these influencing factors. The reaction of the tertiary base olefin, such as isobutylene or isoamylenes, and hydrogen sulfide whereby the corresponding tertiary mercaptan is formed is slightly exothermic. Therefore, in orderthat the temperature of the reaction mixture be controlled within the desired limits, the heat of reaction should be uniformly and readily withdrawn from the reaction zone. This may be accomplished by a proper control of the temperature and rate of flow of the heat transfer medium in the reactor. 'I'he sensitivity of this reaction to temperature in the presence of sulfuric acid is illustrated by the curve in Figure 3.

Referring now to Figure 3, the curves A and B are temperature-yield curves with temperature plotted along the abscissa and yield of .tertiary asa'av'za butyl mercaptan plotted along the ordinate. Each point on the curves represents a single preparation of tertiary butyl mercaptan from isobutylene and hydrogen sulfide under the following conditions. A reaction chamber containtaining a single catalyst tubeinside diameter 22 mm. was used. In each run, three (3) liters per hour of each gas, isobutylene and hydrogen sulfide, were employed. Each run was continuous and varied .in duration from 4 to '1.5 hours with contact times from about 4 to about 6 minutes, which was influenced by temperature, catalyst volume, etc. Each yield of tertiary butyl mercaptan was based upon that fraction of reaction product boiling from 63 C, to 66 C. at atmospheric pressure.

'Appreciable amounts-2 to 6 grams-of elemental sulfur were formed in each run.

Curve A clearly indicates that the process contemplated herein with sulfuric acid as the catalyst is operative over the broad temperature range of 25 C. to about 100 C. A quantity of 95 grams sulfuric acid deposited on 61 grams of wood charcoal was used; and the volume and height in the column were 300 cc. and cm., respectively. It is seen that at atmospheric or room temperature, about 25 C., a yield of about 10% is obtained. The yield increases with increase of temperature until the maximum yield-about 60 %-is obtained in the neighborhood of 80 C. Thereafter, further increase of temperature makes for smaller yields until at about C. (96 C. on the curve), the yield is only about 15%. For practical purposes where yields of 40% and greater are desired. the curve indicates that temperatures within the range of about 60 C. to about 90 C. may be used. With a closer regulation of temperature within the range of about 65 C. to about 85 C., maximum yields of 50% or more are obtained.

Curve A also indicates that sulfuric acid is relatively ineffective within the temperature range of 0 C. to 38 C. as proposed in the aforesaid Patent 1,836,170. For example, the greatest yield of mercaptan within the range proposed in said patent is only about 15%, at 38 C.

Similarly, Curve B indicates that the process contemplated herein with an organic sulfonic acid, illustrated by benzene sulfonic acid, is operative over the broad temperature range of 25 C. to about 100 C. In the several preparations represented by the several points on the curve (B), a quantity of 100 grams of benzene sulfonic acid deposited on 75 grams of granulated wood charcoal was used; this occupies about 250 cc. in the catalyst column. It will be seen that at atmospheric or room temperature, about 25 C., a yield of about 20% is obtained; and at about 100 C., a yield of about 15% is obtained. Within these temperatures, 25 C. and 100 C., however, the yields are substantially larger, the maxirziun yield, about 45%. being obtained at about While Curves A and B were obtained with the operating conditions described above, it will be understood that the slope and breadth of these curves may change with changes in one or more operating conditions. For example, various proportions of reactants may be used instead of three liters of each gas, hydrogen sulfide and isobutylene. In general, however, it appears that these curves substantially represent the catalytic action of sulfuric acid and of organic sulfonic acids in the conversion of the C-4 and C-5 tertiary baseoleilns to their corresponding tertiary mercaptans.

It is one feature of this invention that high pressures are not required. On the contrary, atmospheric or, at most, pressures only slightly greater than atmospheric are used. In order that the reaction be carried out in the vapor` phase, it is necessary that the pressure be less than that pressure at which liquefaction of the hydrocarbon would occur at the operating temperature. It will readily be seen that the use of pressures from about atmospheric to about 4 atmospheres are not such as to require the use of expensive high-pressure reaction chambers. This, of course, is a-decidad economic advantage.

As aforesaid, the proportions of reactants for our process obviously can be varied considerably. Theoretically, the optimum molar ratio of tertiary base oleiin to hydrogen sull-1de would be 1:1. lu some cases, however, maximum yields are obtained when a slight excess of HzS is used. Tertiary base oleflns are notorious for their tendency to polymerize and this polymerization reaction tends to compete with the addition reaction with the resultant formation oi high boiling poly tertiary base oleilns. An excess of HzS, therefore, will increase the yield of mercaptan by aiording greater opportunity for the tertiary base olen- H-iS reaction. This factor of the molar ratio of the reactants naturally will be regulated by the economics of the particular case at hand, that is,

by the relative costs oi hydrocarbon and HaS, and

of their handling and recovery. l

While it is possible, and is contemplated herein, to use the catalyst without a catalyst support, it is preferred that the catalyst be supported on an adsorbent inert carrier. Many such substances may be used for this purpose, typical of which are wood charcoal, cocoanut charcoal, granulated coke, certain clays which are catalytically inactive for the purposes of this invention (as opposed to active non-plastic clays), silica gel, etc. For example, we have found that Wood and cocoanut charcoals exert little, if any, catalytic eiect in the methods of separation and preparation contemplated herein. Wood charcoal, under the same -cai'bon mixture containing the corresponding tertiary base oleiin or the corresponding tertiary base oleiin in the pure form. If the hydrocarbon reactant contains several tertiary base oleflns, the mercaptan product will be a mixture of the corresponding tertiary mercaptans which can be separated into its various components by fractionation.

It is to be understood that this invention is not to be limited to the foregoing typical illustrative examples of the same, but isV to be construed broadly as defined by the language of the appended claims.

We claim:

l. The method of making a tertiary mercaptan from a tertiary base olen selected from the group consisting of isobutylene, trimethyl ethylene and unsymmetrical methyl ethyl ethylene which comprises, passing said tertiary base olefin in the Vapor phase with hydrogen sulde through a reaction zone containing a catalyst selected from the group consisting of an organic sulfonlc acid and sulfuric acid, regulating the flow of said reactants through said reaction zone to provide therein a contact time from a fraction of a second to several minutes and maintaining the temperature of said reactants therein between about 50 C. and about 100 C., whereby said tertiary base olen is converted to the corresponding tertiary mercaptan.

2. The method of making a tertiary mercaptan from a tertiary base olefin selected from the group consisting of isobutylene, trimethyl ethylene and unsymmetrical methyl ethyl ethylene which comprises, passing said tertiary base olefin in the vapor phase with hydrogen sulde through a reaction zone containing a catalyst selected from captan from isobutylene which comprises, passing isobutylene in the vapor phase with hydrogen sulde through a reaction zone containing a catalyst selected from the group consisting of an organic sulfonic acid and sulfuric acid, regulating the flow of said reactants through said reaction zone .to provide therein a contact time from a fraction of a second to several minutes and maintaining the temperature of said reactants therein between about C. and about 90 C., whereby isobutylene is converted-to tertiary butyl mercaptan.

4. The method of making tertiary amyl mercaptan from trimethyl ethylene which comprises passing trimethyl ethylene in the vapor phase with hydrogen sulfide through a reaction zone containing a catalyst selected from the group consisting of an organic sulfonic acid and sulfuric acid, regulating the iiow of said reactants through said reaction zone to provide therein a contact time from a fraction of a second to several minutes and maintaining the temperature of said reactants therein between about 60 C. about 90 C., whereby trimethyl ethylene is cig? verted to tertiary amyl mercaptan.

5. The method of making tertiary amyl mercaptan irom unsymmetrical methyl ethyl ethylene which comprises, passing unsymmetrical methyl ethyl ethylene in the vapor phase with hydrogen suliide through a reaction zone containing a catalyst selected from the ro sistmg of an organic sulfonic acid aid lslfclrric acid, regulating the iiow of said reactants through said reaction zone to provide therein a contact time from a fraction of a second to several minl utes and maintaining the temperature of said reactants therein between about 60 C. and about C., whereby unsyminetrical methyl ethyl etlyl'rrile is converted to tertiary amyl mercaptan.

e method of making a terti r from a tertiary base oleiin seletzelni'op group consisting of isobutylene, trimethyl ethylene and unsymmetrical methyl ethyl ethylene which comprises, passing said tertiary base oleiin in the vapor phase with hydrogen sulde through a reaction zone containing sulfuric acid regulating the flow of said'reactants through said reaction zone to provide therein a contact time from a fraction of a second to several minutes and maintaining the temperature of said reactants therein between about 60 C. and about 90 C., whereby said tertiary base olefin is converted to the corresponding tertiary mercaptan.

7. The method of making a tertiary mercaptan from a tertiary base olefin selected from the group consisting of isobutylene, trimethyl ethylene`and unsymmetrical methyl ethyl ethylene which comprises, passing said tertiarybase olefin in the vapor phase with hydrogen sulfide through a reaction zone containing an organic sulfonic acid, regulating the iiow of said reactants through said reaction zone to provide therein a contact time from a fraction of a second to several minutes and maintaining the temperature of said reactants therein between about 50 C. and about 100 C., whereby said tertiary base olefin is converted to the corresponding tertiary mercaptan.

8. The method of making a tertiary mercaptan from a tertiary base olefin selected from the group consisting of isobutylene, trimethyl ethylene and unsymmetrical methylethyl ethylene which comprises, passing said tertiary base oleiin in the vapor phase with hydrogen sulfide. through a reaction zone containing benzene sul Ionic acid, regulating the flow of said reactants through said reaction zone to provide therein a contact time from a fraction of a second to several minutes and maintaining the temperature of said reactants therein between about 50 C. and about 100 C., whereby said tertiary base olefin is converted to the corresponding tertiary mercaptan.

9. The method of selectively separating a tertiary base olefin selected from the group consisting of isobutylene, trimethyl ethylene and unsymmetrical methyl ethyl ethylene from a hydrocarbon mixture containing said tertiary base olen. a normal olefin, a secondary olen and a saturated hydrocarbon, which comprises: admixing said hydrocarbon mixture with hydrogen sul.. fide; passing the reaction mixture thus formed in' the vapor phase through a reaction zone containing a catalyst selected from 'the group consisting of an organic sulfonic acid and sulfuric acid, regulating the ow of 'said reaction mixture through said reaction zone to provide a very brief contact time therein and maintaining the temperature of said reaction mixture therein between about 25 C. and about 100 C., whereby said tertiary base olefin is converted to the corresponding tertiary mercaptan; and separating said mercaptan from the reaction product so obtained.

10. The method of selectively separating a tertiary base olefin selected from the group consisting of isobutylene,- trimethyl ethylene and unsymmetrical methyl ethyl ethylene from a hydro- `carbon mixture containing said tertiary base olefin. a normal olefin, a secondary olefin and a saturated hydrocarbon, which comprisesz' admixing said hydrocarbon mixture with hydrogen sulde; passing the reaction mixture thus formed in the vapor phase through a reaction zone containing a catalyst selected from the group consisting of an organic sulfonic acid and sulfuric acid, regulating the flow of said reaction mixture through said reaction zone to provide a very brief contact time therein and maintaining the temperature of said reaction mixture therein between about 60 C. and about 90 C., whereby said tertiary base olefin is converted to the corresponding tertiary mercaptan; and separating said mercaptan from the reaction product so obtained.

11. The method of selectively separating a tertiary base olen selected from the group consisting of isobutylene, trimethyl ethylene and unsymmetrical methyl ethyl ethylene from a hydrocarbon mixture containing said tertiary base olefin, a normal olefin, a secondary olefin and a saturated hydrocarbon, which comprises: admixing said hydrocarbon mixture with hydrogen sulde; passing the reaction mixture thus formed y in the vapor phase through a reaction zone containing sulfuric acid, regulating the flow of said reaction mixture through said reaction zone to provide a very brief contact time therein and maintaining the temperature of said reaction mixture therein between about C. and about 90 C., whereby said tertiary base olen is converted to the corresponding tertiary mercaptan; and separating saidmercaptan from the reaction product so obtained.

12. The method of selectively separating a tertiary base olefin selected from the group consisting of isobutylene, trimethyl ethylene and unsymmetrical methyl ethel ethylene from a hydrocarbon mixture containing said tertiary base olefin, a normal olefin. a secondary olefin and a saturated hydrocarbon, which comprises: admixing said hydrocarbon mixture with hydrogen sulfide; passing the reaction mixture thus formed in the vapor phase through a reaction zone containing an organic sulfonic acid, regulating the fiow of said reaction mixture through saidreaction zone to provide a very brief contact time therein and maintaining the temperature of said reaction mixture therein between about 25 C. and about 100 C., whereby said tertiary base olefin is converted to the corresponding tertiary mercaptan; and separating said mercaptan from the reaction product so obtained.

13. The'method of selectively separating a tertiary base-olefin selected from the group consisting of isobutylene, trimethyl ethylene and unsymmetrical methyl ethyl ethyiene'from a hydrocarbon mixture containing said tertiary base olen, a normal olefin, a secondary olefin and a saturated hydrocarbon, which comprises: admixing said hydrocarbon mixture with hydrogen sulfide; passing the reaction mixture thus formed in the vapor phase through a reaction zone containing 'benzene sulfonic acid, regulating the flow of said reaction mixture through said reaction zone to provide a very brief contact time therein and maintaining the temperature of said reaction mixture therein between about 25 C. and about 100 C., whereby said tertiary base olefin is converted to the corresponding tertiary mercaptan; and separating said mercaptan from the reaction product so obtained.

14. In a. method for making a tertiary mercaptan by reacting a tertiary base olefin vapor with hydrogen sulfide in the presence of a catalyst selected from the group consisting of an organic sulfonic acid and sulfuric acid, the improvement which comprises: regulating the flow of said olefin vapor and hydrogen sulfide with respect to said catalyst to provide a contact time therein from a fraction of a second to several minutes and maintaining a reaction temperature therein between about 60 C. and about 90 C.

15. In a method for making a tertiary mercaptan by reacting a tertiary base olefin vapor with hydrogen sulde in the presence of sulfuric acid, the improvement which comprises: regulating the ow of said olefin and hydrogen sulde with respect to sulfuric acid to provide a contact time therein from a fraction of a second to several minutes and maintaining a reaction temperature therein between about 60 C. and about 90 C.

16. In a method for making a tertiary mercaptan by passing a vapor phase mixture containing a tertiary base olefin and hydrogen 'sulde through a reaction zone containing sulfuric acid, the improvement which comprises: regulating the flow of said vapor phase mixture through said reaction zone to" provide a contact time therein from a .fraction of a second to several minutes and maintaining the temperature of said vapor phase mixture therein between about 60 C. and about 90 C.

17. In a method for making a tertiary mercaptan bypassing a vapor phase mixture containing a tertiary base olen and hydrogen sulde through a reaction zone containing a catalyst selected from the group consisting of an organic.

sulfonic acid and sulfuric acid, the improvement which comprises: regulating the ow of said vapor phase mixture through said reaction zone to provide a contact time therein from a fraction of a second to several minutes and maintaining the temperature of said vapor phase mixture therein between about 60 C. and about 90 C.

18. The method of making a tertiary mercaptan from a tertiary base olefin which comprises, passing said olefin in the vapor phase with hydrogen sulde through a reaction zone containing a catalyst selected from the group consisting of an organic suli'onic acid and sulfuric acid, regulating the ow of said reactants through said reaction zone to provide therein a contact time from a fraction of a second to several minutes and maintaining the temperature of said reactants therein between about C. and about C., whereby said olen is converted to the corresponding mercaptan.

19. The method of selectively separating a tertiary base olen selected from the group consisting of isobutylene, trimethyl ethylene and unsymmetrical methyl ethyl ethylene from a hydrocarbon mixture containing said tertiary base olen and at least one non-tertiary base olen, which comprises: admixing said hydrocarbon mixture with hydrogen sulde; passing the reaction mixture thus formed in the vapor phase through a reaction zone containing a catalyst selected from the group consisting of an organic sulfonic acid and sulfuric acid, regulating the ow of said reaction mixture through said reaction zone to provide a very brief contact ltime therein and maintaining the temperature of said reaction mixture therein between about 25 C. and about 100 C., whereby said tertiary base olen is converted to the corresponding tertiary mercaptan; and separating said mercaptan from the reaction productl so obtained.

DARWIN E. BADERTSCHER.

HARRY L. COONRADT. `DUNCAN J. CROWLEYl- 

